The present invention relates to railway cars and more particularly to a railway car of the open gondola type in which cargo is loaded and unloaded through the open top of the car.
Gondola railway cars are normally employed to carry bulk cargoes of granular or lump-form materials such as coal, sand, and gravel. Conventional gondola cars are of metal construction and have a continuous center sill structure extending the length of the car, and a flat bottom carried atop the center sill. Many of such cars are of a standard size in order to be unloaded by a dumper which turns the entire car upside down.
Teoli U.S. Pat. No. 3,713,400 discloses a gondola railway car in which there is a parabolic shaped bottom between the trucks, but there is no full-length center sill.
Jones et al. U.S. Pat. No. 4,361,097 discloses a gondola railway car having a continuous full-length center sill and a pair of longitudinally arranged curvilinear troughs arranged one on each side of the center sill.
Landregan U.S. Pat. No. 4,331,083 discloses a gondola car in which a longitudinally central portion of the center sill is lower than the portions at the ends of the car.
Heap U.S. Pat. No. 4,408,542 discloses a gondola car with a full-length center sill and a longitudinal curvilinear trough extending the full width of the car and extending beneath the center sill structure in a longitudinally central portion of the car.
While the gondola railway car structures previously known, such as those disclosed by the patents mentioned above, have certain advantages over the previously known gondola cars, particularly regarding the height of the center of gravity, such cars are still heavier than is desired for most efficient use.
Particularly in gondola cars for use in carrying coal, aluminum has been used to replace certain portions of structures previously made of steel, because of the ability of aluminum to withstand the corrosive effects of impurities, such as sulfur, commonly found in coal. Such aluminum structure can also reduce the weight of such cars, allowing a greater weight of cargo to be carried on each car, but aluminum construction is quite expensive, even considering the possibility of recovery of the aluminum from cars after their useful lifetime has ended. Therefore, it is still desired to provide a gondola railway car of adequate strength, but which is yet lighter than steel, less costly to construct and maintain, and more durable than previously available railway cars for carrying such types of cargo.